There is a conventionally known technique in which a contact member is mounted on the surface of a around pattern on a printed circuit board and, in that state, the printed circuit board is fixed in such a manner that the contact member is pressed against a grounding conductor, such as a chassis or the like. Thereby a ground pattern on the printed circuit board is electrically grounded to the grounding conductor via the contact member. Especially, in recent years, as more and more instruments having microcomputers built therein have been manufactured with the development of computer technology, the aforementioned technique is now indispensable for grounding printed circuit boards within such instruments.
This kind of contact member is likely to be formed by a conductive elastic sheet to ensure electrical conduction between a ground pattern on a printed circuit and a grounding conductor. Also, this contact member is sometimes combined with a conductive elastic body for the purpose of electromagnetic shield for use.
For example, in Publication of Japanese Unexamined Patent Application No. 2002-510873, situation is disclosed where a conductive gasket member is provided to a contact member made of plate metal in which a pair of spring-like finger parts are bent back from an end.
When a contact member is disposed between a ground pattern on a printed circuit and a grounding conductor such as a housing etc., tightening the cover of the housing by a bolt means risking that the contact member will be plastically deformed. This would result in the contact member losing its spring characteristics and not being able to elastically recover toward its original configuration. Once elastic resilience is lost, for example, when the housing is opened and closed repeatedly, the contact between the contact member and the housing may not be maintained, resulting in a chance of conductive failure.
The conductive gasket, disclosed in FIG. 10 of the Publication of Unexamined Japanese Patent Application No. 2002-510873, is considered by some to resist against the force which is attempting to crush a finger of the contact member. However, there is no reference in the above Japanese Patent Application to the problem of the case in which the elastic resilience of the finger is lost, and no description of measures to guard against the situation in which elastic resilience of the finger is lost.